Zipf's law for pore ranking and pore anisotropy.

In this work it is shown that the range of Zipf's law for the ranking of random pores in solids upholds for ∼10 orders of magnitude, from nm pore sizes in laboratory-made materials, to cm pore sizes occurring in solidified volcanic magmas. Also it is demonstrated that for MCM-type materials with organized mesopores, the out-of-trend data in the Zipf plots, corresponding to the sudden pore filling during N2 adsorption, can be used for the convenient estimation of local pore anisotropy.